Trailing arm furrow opener assemblies are well known in the agricultural industry. These assemblies are spaced across the width of a seeding implement and each comprises a lengthy arm that is pivotally attached at the front end thereof to the implement frame about a horizontal pivot axis oriented perpendicular to the operating travel direction such that the arm can pivot up and down with respect to the frame. A packer wheel is mounted to a rear end of the arm and one or more furrow opener shanks extend downward from the arm forward of the packer wheel. A bias element such as a spring or hydraulic cylinder exerts a downward bias force on the arm to push the furrow opener mounted on the bottom of the shank into the soil to create a furrow, and the furrow depth is set by the relative positions of the packer wheel and furrow opener.
Such a trailing arm furrow opener assembly is disclosed for example in U.S. Pat. No. 7,159,523 to Bourgault et al. particularly in FIG. 1 thereof. Similarly U.S. Pat. No. 5,396,851 to Beaujot discloses such a trailing arm with two furrow opener shanks with knife type furrow openers attached to the bottoms thereof and configured to make two slightly laterally spaced furrows, one for seeds and the other for fertilizer. U.S. Pat. No. 5,609,114 to Barton discloses a similar trailing arm with one or two disc type furrow openers mounted to the arm.
Seeding operations require that a consistent furrow depth be maintained. The desired seeding depth will also vary depending on the crop being planted, with a deeper furrow depth for larger seeds such as corn and peas and a shallower furrow depth for smaller seeds such as canola. In many common trailing arm type seeding implements the frame is mounted on fixed wheels so the distance from the frame to the ground surface is constant. The furrow opener assemblies are then pivoted about the front arm axis to move between an operating position engaged in the ground and a transport position above the ground. The furrow depth is adjusted by moving each packer wheel up or down with respect to the corresponding furrow opener. A typical seeding implement may have 80 or more furrow opener assemblies, and changing the furrow depth is a time consuming operation.
Maintaining consistent furrow depth is problematic with trailing arm furrow opener assemblies with a single arm such as that of Bourgault, Barton, and Beaujot in uneven terrain where the distance between the frame and the ground varies. As the vertical distance of the frame above the ground varies the trailing arm moves up and down about its pivotal attachment to the seeder and the angle of the trailing arm changes such that the distance from the middle portion of the arm, where the furrow opener is attached, to the ground varies, and thus the actual depth of the seed furrow varies.
While this property is problematic for furrow depth consistency in uneven terrain, it is also useful for providing a relatively quick way to change the furrow depth when changing from one crop to another. The implement frame may be mounted on movable wheels so the distance between the frame and the ground surface can be adjusted, and such an adjustment of the frame height also changes the furrow depth.
To improve the consistency of the furrow depth Bourgault et al. also disclose, in FIGS. 5-9 of U.S. Pat. No. 7,159,523, a trailing arm formed by upper and lower parallel arms of equal length. Front ends of the arms are pivotally connected to a front link member fixed to the implement frame, and rear ends of the arms are pivotally connected to a rear link member. Such a parallel link assembly has the property that the rear link member is maintained in a constant horizontal and vertical orientation through the vertical range of motion without tilting forward or rearward. The front link member thereof is fixed to the implement frame and the rear packer wheel and the furrow opener are fixed to the rear link member. Thus as the packer wheel moves up and down relative to the frame in uneven terrain, the packer wheel and furrow opener move together vertically and so the furrow depth is maintained at a constant depth. In these parallel arm assemblies the furrow depth is adjusted by the time consuming operation of moving each packer wheel up or down with respect to the corresponding furrow opener.
A further issue with seeding implements is the fore and aft presentation angle of the furrow opener with respect to the ground surface. Furrow openers typically include a pointed front end or tip that is oriented to engage the soil and draw the furrow opener into the soil. The product tube deposits agricultural product generally behind the tip after the furrow has been formed and before the soil moved aside to create the furrow can drop back into the furrow so that the product is at the bottom of the furrow, and the soil falls back on top of the product. Some furrow openers make more than one furrow, with product divided between the furrows, or with different product directed to each furrow.
Thus as the fore and aft presentation angle changes, the angular relationship between the furrow opener and the soil, which dictates the form of the furrow made, and the relationship between the furrow opener and the product tube, which dictates the location of the agricultural product in the furrow, changes as well. In a conventional trailing arm furrow opener assembly with a single arm, as the arm moves up and down with respect to the frame, the presentation angle changes.
Parallel arm assemblies fix the fore and aft presentation angle of the furrow openers with respect to the ground as the furrow opener moves up and down in uneven terrain such that the presentation angle does not change.
U.S. Pat. No. 7,549,481 to Lung et al. addresses the issue of providing a consistent presentation angle by providing a parallel arm assembly where only the furrow opener is attached to the rear link member and the packer wheel is attached to a rear end of one of the upper and lower arms of the parallel arm assembly. In this arrangement the parallel arm assembly moves up and down in the same manner as a single arm furrow opener assembly, with the furrow depth varying in uneven terrain, however the presentation angle is maintained constant as the arm assembly moves up and down. As in a conventional single arm assembly, depth adjustment can be accomplished by raising and lowering the implement frame with respect to the ground.
It is also known to add remote actuation to each trailing arm opener to adjust the position of the packer wheel to change the depth of the furrow as disclosed in United States Published Patent Application Number 2011/0282556 of Klenz et al. However this solution to improve the ease and efficiency of depth adjustment on each opener is expensive and adds reliability concerns due to the added electronics in a somewhat harsh operating environment.